Buy:
-Double jump
-Air Dash
-More speed movement
(Not sure which of them are trully necesary)

After purchasing these perks, just enter a map and enjoy the flight by pressing jump and dash (shift) all the time.
If not working try aiming up. Sometimes the player loses inercy or something and starts falling but you can just do it again.
Another tip is to purchase double bow and just blow everything from the sky.